IIRC that Segate unit uses a single 2.5" hdd that will max out loooong before saturating either interface. So I would say the real world difference would be so close to zero that it would not matter. As long as your computer can handle the overhead AND push data fast enough either USB 3 or ThunderBolt will be more than 'good enough'.

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I've been using USB 3.0 to backup my system to a RAID1 box, so the speeds when writing should be comparable to a single drive. With that, I usually get 80-90 MB/s while writing - which is in the right ball park for the WD Greens I have in there. So, I would say in most cases between USB 3.0, TB, and even eSATA for that matter, the drive will be what limits the performance.